Impaired fibrinolysis and lower levels of plasma α(2)-macroglobulin are associated with an increased risk of severe asthma exacerbations

Recently we have reported that asthma is associated with enhanced plasma thrombin formation, impaired fibrinolysis and platelet activation. In the present study we investigated whether described prothrombotic blood alterations might predispose to thromboembolic events or asthma exacerbations. In 164 adult asthmatics we assessed clinical events during 3-year follow-up and analyzed their associations with measured at baseline prothrombotic blood parameters. Data were obtained from 157 (95.7%) of the asthma patients. We documented 198 severe asthma exacerbations (64/year), which occurred in 53 subjects (34%). These patients were older (p = 0.004), had worse asthma control (p = 0.02) and lower spirometry values (p = 0.01), at baseline. Interestingly, this subgroup had longer clot lysis time (CLT), as well as lower α(2)-macroglobulin (p = 0.038 and p = 0.04, respectively, after adjustment for potential confounders). Increased CLT and lower α(2)-macroglobulin were demonstrated as independent predictors of asthma exacerbation in multiple regression model. Moreover, we documented two episodes of deep vein thrombosis (1.3%), and eight acute coronary syndromes (5.1%). Patients who experienced thromboembolic events (n = 10, 6.4%, 2.1%/year) had lower α(2)-macroglobulin (p = 0.04), without differences in efficiency of fibrinolysis and thrombin generation. Impaired fibrinolysis and lower levels of α(2)-macroglobulin might predispose to a higher rate of asthma exacerbations, suggesting new links between disturbed hemostasis and asthma.